NATURAL ARRANGEMENT. 



XXV 



Perhaps he has discovered that his plant belongs to Rubiaceas ; he will then have learned that all vegetables 

 with opposite entire stipulate leaves, and a monopetalous superior corolla, are also Rubiaceous. If a fragment 

 of the leaves and stem only of such a plant were afterwards submitted to him for examination, he would 

 recognise its affinities, and remember that it was Rubiaceous, and, being aware of that fact, he would be able 

 safely to infer that its calyx and corolla would be of a particular nature ; that if the roots afforded any color 

 for dying, it would be red ; that the medicinal properties of the bark, if any, would be tonic, astringent, and 

 febrifugal; and that its seeds would be of the same nature as those of coffee; and, finally, its geographical 

 position would be tolerably certain to him. 



The principal difficulty which has to be encountered by the student of the Natural System of plants is caused 

 by the want of an introduction to the subject, accompanied by the characters of the several orders; this is 

 indeed removed as far as the British Flora is concerned by the publication of Dr. Lindley's Synopsis, in which 

 the essential characters of all the wild flowering plants of this country are stated and analysed ; but it still 

 exists with respect to the vegetable kingdom in general. It is obviously impossible to overcome this difficulty 

 here; all that we can do is to point out the characters of the great divisions under which the orders are 

 arranged ; even this necessarily very imperfect mode of treating the subject will probably remove some of the 

 inconvenience that is at present experienced. 



Plants considered with reference to their general structure, are separated into two grand divisions called 

 Cellula^res and Vascula^res. 



The Cellulares answer to the Linnean Cryptogamia, and are also called Acotyledbneae ; the Vasculares 

 answer to the rest of the Linnean system, which is sometimes called Phanerogamia and Cotyledoneas. 



C ellula^res, Cryptogamous, or Acotyledonous, plants are all, therefore, different terms denoting the same 

 combination of vegetables. The first term is here adopted in preference to the others as expressing the most 

 obvious character upon which the division depends, namely, the cellular, not vascular, structure of the plants 

 composing it. Cellular plants are formed entirely of cellular tissue (fig. 1.), without spiral vessels; or in 



a, Longitudinal section of a stem. f, Crustaceous thallus of a lichen, with shields. 



b, Transverse section of a stem. g, Fungi of the highest dignity. 



c, Stem of a moss, with leaves and theca, or seed-case. h, i, Fungi of the lowest rank. 



d, Leaf of a moss magnified. k, Conferva magnified. 



e, Leafy thallus of a lichen, with shields. 



more familiar terms by having no veins in their leaves if foliaceous, and not forming wood ; they also are 

 destitute of perfect flowers. The lower tribes, such as Fungi and AlgjE, are destitute of leaves, and in some 

 points approach the animal kingdom so nearly as to be scarcely distinguishable. In the highest tribe, Ferns, 

 apparent veins are formed in the leaves ; but as they are not supplied with spiral vessels, they cannot 

 be considered more than analogous to the veins of other plants. Ferns, however, hold the intermediate station 

 between Cellulares and Vasculares, and are chiefly retained among the former on account of their perfect 

 accordance in other respects. In the whole of Acotyledons, it is unnecessary to examine the seed for the 

 purpose of determining whether it has one cotyledon, several cotyledons, or none, the structure of the perfect 

 plant giving the most obvious and satisfactory evidence. 



Vascula"res, Pimsnogamous, or Cotyledonous, plants, are also separated into two great classes called 

 End6genes or Monocotyledons, and Ex6genes or Dicotyledons, both which are distinguished as accurately 

 by their obvious physical structure as they are by the minute and obscure peculiarities of the seed. They are 

 all formed with cellular tissue, woody fibre, and spiral vessels {fig. 2.), and their leaves are traversed by veins ; 

 the last character is sufficient for practical purposes, if it is remembered that they also bear perfect flowers, 



/, Vertical section of a vascular stem. o, Leaf of a dicotyledonous plant. 



m, Woody fibre, or elongat-J cellular tissue. p, Leaf of a inonccot^ledonous plant, 



n, Spiral vessel - - 



